In general, an air conditioner is a cooling/heating device which cools an indoor area by repeatedly performing an operation of sucking indoor hot air, heat-exchanging it with a low temperature refrigerant, and discharging the same to the indoor area, or heats the indoor area through the opposite operation. The air conditioner includes a compressor, a condenser, an expansion instrument, and an evaporator to form a series of cycle circulating a refrigerant.
Here, the compressor is a device for compressing a refrigerant at a high temperature and high pressure. To this end, essentially, oil in a fine particle form is mixed with the refrigerant. However, when the mixed refrigerant is introduced into the evaporator, it forms an oil film on a surface of a heat exchanging pipe disposed therein, degrading heat exchange efficiency of the evaporator.
Meanwhile, in order to enhance refrigerant heat exchange performance within the evaporator, a supercooling heat exchanger is installed between the condenser and the expansion instrument in order to further cool the refrigerant before the refrigerant is introduced to the evaporator through the expansion instrument from the condenser, in some cases.
However, although the supercooling heat exchanger advantageously enhances the refrigerant heat exchange performance within the evaporator, heat released from the supercooling heat exchanger after heat-exchanging with the refrigerant is discarded helplessly, resulting in an increase in a loss of energy due to the installation of the supercooling heat exchanger.